Requested by @Pigsonthewing on Github to add an option to be able to scroll instead of left/right swipe while moving to next chapter.

Note: While vertical scrolling is already there in the app, it does not scroll when moving to the next chapter, which requires left/right swipe in the current situation.

Task:

• If scroll is enabled, show a sub option to called "Chapters" with two selection options. First option is "Up/Down" second is "Left/Right". By default Left/Right is selected and if Up/Down is selected, chapters should be switched by swiping up or down (at the end or start of the current chapter)
• When Up/Down is enabled, then the existing left/right chapter navigation should be disabled and vice versa

Related task: T406912

Note:

• T406893 has added a book completion percentage indicator bar, test and take care of while implementing scroll for continuous chapter.
• Check that the feature for chapter jumps from the Contents tab at the top menu remains functional while implementing scroll for continuous chapter.